- Barebones world (just some land)
- Console output, relevant debug text
- Simple collision/Input
- More complex UI
- Refine World
- Refine UI
- Repeat 5-6 until gold
In a production environment normally you have a set of features you're responsible for, so knowing what to work on is rarely an issue (esp. with publishers
The advantage of working indie is that once things are working on a very basic level, you can decide what you want to do when you want to do it.
If I could offer some advice though, try not to be too jumpy between systems. Lots of bugs happen that way.